GEOLOGY OF THE AREA AROUND GABAL EL-KII.ARAZA, NORTHERN EASTERN DESERT, EGYPT.

Abstract

The present work deals with the geology of the area around Gabal El-Kharaza between Latitudes 27° 50' and 27° 56' 30" Nand Longitudes 32° 45' and 32° 58' E. Field mapping revealed that the basement rocks in the study area include the following rock units, from older to younger, quartz bearing diorite, Dokhan volcanics and younger granites.

The studied Dokhan volcanics are classified petrographically into andesites, dacite, rhyodacite and pyroclastics. The andesites include porphyritic and non­ porphyritic varieties. The pyroclastics comprise dacite and rhyodacite crystal and lithic tuffs as well as fine tuffs, agglomerate and ignimbrites. Geochemical investigations indicate that the studied Dokhan volcanics have calc-alkaline nature and generated in volcanic arc environment.

The younger granites include biotite hornblende granodiorite and muscovite biotite granodiorite. The biotite hornblende granodiorite are composed essentially of plagioclase (30-35 %), quartz (20-25 %) and potash feldspar (15-20 %). On the other hand, the muscovite biotite granodiorite are composed mainly of quartz (35-40 %), plagioclase (20-30 %), potash feldspar (10-15 %) together with biotite (5-10 %) and muscovite (2-4 %). Iron oxides, zircon and apatite are the accessory minerals. The biotite hornblende granodiorite intrudes the quartz bearing diorite and the Dokhan volcanics with sharp contacts and are intruded by muscovite biotite granodiorite.